It is fundamentally known that sulfones can form .beta.-hydroxysulfones with aldehydes and ketones and that the sulfonyl group can be eliminated in a reductive manner after the dehydration of the .beta.-hydroxysulfone to the vinylsulfone. The known reduction methods are, however, generally suitable only for simply molecules and are often not stereospecific. For example, the reduction with sodium dithionite and sodium hydrogen carbonate is for the most part not suitable or only poorly suitable for polyenes. On the other hand, the .beta.-hydroxysulfones are not very stable and in the case of the present polyene systems can not be prepared, since evidently reversible decomposition occurs.
The hitherto known applications of sulfones to the manufacture of carotenoids have therefore been concerned with reactions with halides, esters etc to give sulfones which have the sulfonyl group on a saturated C--C bond and from which the sulfonyl group can be eliminated by reaction with base.